A recent Supreme Court ruling on pharmaceutical safety warnings is upending a costly wave of product-liability lawsuits against some of the world's largest generic-drug manufacturers. At issue is whether a generic-drug company can be sued for failing to strengthen its warning labels beyond those of the branded versions. Last year, a Las Vegas state jury slapped a $500 million judgment against Teva Pharmaceutical Industries Ltd. and Baxter International Inc. on the grounds that the companies failed to adequately warn doctors against the dangers of reusing vials and syringes when they administered propofol, a generic sedative.